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From: jdye@ADS.COM (John W. Dye Jr.)
Newsgroups: comp.graphics
Subject: Image Contouring algorithm wanted
Message-ID: <_}*^0+=@ads.com>
Date: 14 Nov 90 21:29:59 GMT
Sender: usenet@ads.com (USENET News)
Organization: Advanced Decision Systems
Lines: 22

Sorry if this is a subject that has been discussed before, but I
waited until the "monthly message" came out and found no mention
there, so here goes.

  I need an algorithm for creating contour lines on a discretely
sampled surface (a 2d image).  I would like to be able to vary the
distance (in value space) between the contours.  What I want to
produce is a graphic overlay like the elevation contours on a map.

  Since my graphics environment is non-standard, I probably can't
easily use previously written software, so I am more interested in
the "central" mathematics of the algorithm than any specific 
implementations.

	Please respond via email if you can help with a reference or
with a pseudocode (or a realcode) example of the contouring algorithm.

Thanks,

JD
John Dye
jdye@ads.com